Method for determining the quantity of an appropriate chemical that should be added per unit of volume of water in order to fit it for use in the arts



STATES PATENT OFFICE.

CYIVUfi WM. RICE, OF PHILADELPHIA; PENNSYLVANIA.

METHOD FUR DETERMINING THE QUANTITY OF AN APPROPRIATE CHEMICAL THAT SHDULD BE ADDED PER UNIT 0F VOLUME OF WATER IN ORDER TO FIT IT FOR- USE IN THE ARTS.

neonate.

No Drawing.

Some water contains What is called te mporary and permanent hardness, and it is customary to treat such-water by the addition of chemicals adapted to remove or absorb the hardness so as to fit the water for use in boilers and for other purposes. The

hardness of a supply of water frequently changes so that it is often necessary to ascertain at comparatively short intervals of time how much of the appropriate chemical should be added to correct the, changing hardness of the water.

The principal object of the present inven tion is to provide a, method of ascertaining the quantity of chemical required to remove temporary and permanent hardness from water which is so quick and easily practiced that even comparatively unskilled persons can make the ascertainment in a very short time and so insure proper treatment of the water supply.

Generally stated,.the method of ascertaining quantity of an appropriate chemical required to remove the temporary and permanent hardness as it exists from time to time in a given water supply, which embodies my invention, consists in treating a measured sample of the water with an appropriate chemical for removing temporary and permanent hardness, using such chemical in excess under heat control and determining quantitatively the unused quantity and change nature of such chemical.

Free or half bound carbonic acid present as bicarbonate is usually referred to as temporary hardness, and sulphates of calcium and magnesium are usually referred to as" permanent hardness.

In practicing thepresent invention there is added to a measured quantity or sample of the water to'be treated sodium carbonate Specification of Letters Patent.

Patented Feb. 7, 1922.

Application filed July 26, 1918. Serial No. 246,829.

lents, in excess of the quantity required to destroy or absorb any permanent and -temporary hardness that might possibly be present. For example, to one hundred cubic centimeters of water there is added five cubic cent1meters of one-fifth normal solution sodium carbonate or its equivalent. The sample may then be boiled in .a bath. This promotes the re-action. Thereafter the sample is filtered. The result of this is that calcium and magnesium sulphates are converted into carbonates and precipitated,thus removlng though not ascertaining the quantity of the permanent hardness from the sample, and that sodium bi-carbonate and sodium sulphate are formed and are present in the filtrate along with sodium carbonate. It may be remarked that sodium bicarbonate in the resence of excess sodium carbonate is stab e even when the solution is boiled within a water bath. The filtrate containing sodium as bi-carbonates and carbonates and also sodium sulphate, is titrated with the same mineral acid, as sulphuric 'acid or hydrochloric acid of known strength or standard solution,.first against an indicator of the phenolphthalein class. which is peculiarly sensitive to carbonic acid, until the color of the indicator is destroyed, and then against an indicator of the cochineal class, which is more sensitive to alkalinity than indicators of phenolphthalein class. The quantity of acid required in the phenolphthalein titration does not exactly correspond to the quantity of sodium carbonate present 'but must be multiplied by two, so that twice the quantityof acid represents the quantity of carbonates introduced into the waterand unused in any of the reactions. The quantity of acid required in the cochineal titration minus twice the quantity of acid used in the .phenolphthalein titration represents the quantity of carbonate of sodium used to replace the calcium or magnesium bicarbonates originally present in the sample'of water and so is a measure of the temporary hardness. The total amount of carbonate of sodium originally introduced minus the quantity of acid used for the cochineal titration, which represents the unused carbonate of sodium and the amount of carbonate of sodium used to replace the calcium and magnesium bicarbonate originally present in the water, represents the quantity of carbonate of sodium used in the reaction by which the permanent hardness was precipitated. For example, let .2, indicate in terms of acid the total amount of sodium 1 carbonate or hardness removing chemical,

and m, the amount of acid used in the first titration, and 'j, the amount of acid used in the second titration. Then y-.2oa:temporary hardness and zy:permanent hard ness. In the described process neither the temporary nor permanent hardness were acsorption b the carbonates of sodium of the half-boun carbonic acid gas from 'its loose combination with the carbonates of calcium and magnesium and also of the carbonic;

1 acid gas as it exists free in the water and hardness.

forms by these means the bicarbonates of sodium. The carbonates of sodium under the heat control of a water bath act as a carrier for the elements causing temporary The determination is in termsof qu'antityof acid or' standard solution used and from thischemists can calculate or ascertain the quantity of an appropriate chemical, as carbonateor hydrate of sodium orv Y potassium or their equivalents that should be added per unit of volume of the-1supply to free it from both the permanent and tem-' porary hardness. In actual practice, I sim-. plif' the'commercial application of my process y providing a chart raduated to show how much by wei ht o an appropriate chemical or chemica s is to be added to each unit of volume of water for variousincrements in volume of mineral acid or standard solution used in the manner described. Phenolphthalein and cochineal are examples of substances adapted to o erate in the man: ner described in the volumetric analysis above explained. Y The feature of the invention isthe use of sodium or potassium carbonate in quantities suflici'ent to destroy in the'water, being tested, both the sulphates of lime and magnesia and also absorb without their dis-association by heat all free or half-bound carbonic acid gas contaihedin waters as carbonic acid. or the bi-carbonates of lime and magnesia,'the resulting carbonates or bi-carbonates of sodium or potassium indicating through a single acid titrationthe temporary or permanent hardnesses to be overcome in order to fit the water ,for use in' the arts. The removal of temporary and and the second indicates the permanenthardness from water results in the destruction of bacteria and the clarification of the water, so that my invention is useful not only in connection with water supplies but also in connection with sewage and like waste. 1

What I claim is: v 1. The method of ascertaining the quantity of an appropriate chemical per unit. of

volume that should be added to remove hardness from a water supply, which consists in adding a measured quantity of a hardness removing chemical in excess of the quantity required to remove the total hardness from a measured sample of such water,

separating the resultant precipitate from the liquid -by filtration, titratingthe filtrate a ains t'two indicators of which the first in-1 dicates the quantity of the chemical unused quantity unused and the quantity used in finding the necessary' factors forascertaining the result, substantially as described. I

2. The method of ascertaining the quanvolume that s ould beadded to remove hardness from a water supply, which consists 1n adding a measured quantity of a hardness removing chemical in excessof the quantity.

sum of the -destroying temporary hardness.. and thus tity of an a ropriate chemical er unit of PE P required tormove the total hardness froma measured sample of such water and boiling the admixture in a water bath, se arating the resultant precipitate from the llquid by filtration, titrating the filtrate against two indicators of which the first indicates the quantity of the chemlcal unused andithe second indicates the sum of the quantity.-

unused and thequantityused in destroying temporary hardness and thus finding the necessary factors for ascertaining the result,

substantially as described.

3. The method H tity of an appropriate chemicalper. unit of volume that should be added to remove hardness from" a water' supply, which consists in adding removing chemical in excess of the quantity required to remove the total hardness from a measured sample of such water, subjecting a' measured, quantity of ahardness.

fascertaining -quan iiithe admixture to a limited degree of heat appropriate for preventin the destruction of the'bi-carbonates of sodium and filterin and'titrating' the filtrate againsttwo indicators of which the first indicates'the quamtit of the chemical .unused and the second in 'icates'the sum of thevquantity unused and the quantity used in destroying temporary hardness and thus finding the necessary factors for ascertaining the result, substantially as described; I I

tityof an appropriate chemical per uni-tier volumethat s ould be added. to remove tern porary hardness iroma' water supply, that 4. In the process ofascert'aining the quan- I v 5. The method of ascertaining the quan- ,tity of appropriate chemicals per unit of volume, that should be added to remove the temporary hardness and permanent hardness from a water supply, which consists in adding a measured quantity of a hardness removing chemical in excess of the quantity ipguired to remove the total hardness fromv a single measured sample of such water, separating the resultant precipitate from the liquid 'by filtration, titrating the filtrate against two indicators, of which the first indicates the quantity of the chemical unused, and the second indicates the sum of the quantity unused andthe quantity used in destroying temporary hardness, and the difference between the total quantity of hardness removing agent introduced and the sum of the quantity used to destroy the temporary hardness and the quantity unused equals the quantity required to.destroy the permanent hardness, and thus finding the necessary factors for ascertaining the result, substantially as described.

6. The method of ascertaining the quantity of appropriate chemicals per unit of volume that should be added to remove the temporary hardness and permanent hardness from a water supply, which consists in adding a measured quantity of a hardness removing chemical in excess of the quantity required to remove the total hardness from a single measured sample of such water, and

boiling the admixture in a Water bath,-sepa-' rating the resultant precipitate from the liquid by filtration, titrating' the filtrate against two indicators, of which the first indicates the quantity of the chemical unused, and the second indicates the sum of the I quantity unused and the quantity used .in destroying temporary hardness, and the difference between the total quantity of hardness removing agent introduced and the sum of the quantity used to destroy the temporary hardness and the quantity unused equals the-quantity required to destroy the permanent hardness, and thus finding the necessary factors for ascertaining the result, substantially as described.

7. The method of ascertaining the quantity of appropriate chemicals per unit of volume, that should be added to remove the temporary hardness and permanent'hardness from a. water supply, whichvconsists in adding a measured quantity of a hardness removing chemical in excess of the quantity required to remove the total hardness from a single measured sample of such water, subjecting'the admixture to a limited, degree of heat appropriate for preventing the destruction of the bi-carbonates of sodiuin and filtering, and titrating the filtrate against two indicators, ,of which the first indicates the quantity of the chemical unused, and the second indicates the sum of the quantity unused and the quantity used in destroying temporary hardness, and the difi'erence between the total quantity of hardness removing agent introduced and the sum of the quantity used to. destroy the temporary hardness and the quantity unused equals the quantity required to destroy the permanent hardness, and. thus finding the necessary factors for ascertaining the result, substantially as described.

8. The-process of ascertaining the quantity of appropriate chemicals per unit of volume that should be added to remove temporary hardness and permanent hardness from a water supply, that improvement which consists in subjecting an admixture of a single sample of the waterand carbonate of sodium in' excess to a temperature appropriate for preventing the destruction of the bi-carbonates of sodium by heating it in a 1 boiling bath, filtering and titrating the filtrate against two indicators, substantially as described.

' CYRUS WM. RICE. 

